With regard to an electronic device such as an acoustic device, an image device or the like in recent years, there has been intended exponentially an improvement of performance in comparison with a conventional one, on the basis of a noticeable progress of a digital technology.
On the basis of the improvement of performance of the electronic device, there has been strongly requested from a market an improvement of performance in a loudspeaker used in the electronic device.
In the loudspeaker in which the improvement of performance is strongly requested, it is essential to correspond to a high performance of a vibrating part centered on a diaphragm occupying a great weight for determining a sound quality in constituting parts of the loudspeaker.
As a part of a correspondence for making the vibrating part centered on the diaphragm high in the performance, there is attached a high value to a sound making and a characteristic making which satisfy user needs required per respective fields and respective intended uses.
A structure which can achieve the sound making and the characteristic making satisfying a user needs is a paper making part having an advantage which can fine adjust a characteristic and a sound quality as the loudspeaker, and a development of the paper making part has been developed.
A description will be given of a manufacturing method of the conventional paper making part for the loudspeaker with reference to FIG. 9 by exemplifying a diaphragm.
FIG. 9 is a process chart showing a manufacturing method of a conventional paper making diaphragm for the loudspeaker.
As shown in FIG. 9, a material of the paper making diaphragm for the loudspeaker is thrown in a beater containing a water, and is beaten finely in accordance with a beating step for some days.
Next, the beaten material is paper-made on a metal mold and a metal net arranged on the metal mold in accordance with a paper making step, whereby only a water content is discharged, and is formed in a shape serving as a paper making diaphragm for the loudspeaker in which the material is piled up.
Next, in accordance with a pressurizing step, the material of the piled-up paper making diaphragm for the loudspeaker is heated and pressurized, and the remaining water content is evaporated.
Next, in accordance with a working step (a drawing step), an outermost peripheral portion to be unnecessary and a center hole portion for inserting a voice coil thereto are drawn by the metal mold.
In accordance with the steps mentioned above, the conventional paper making diaphragm for the loudspeaker is finished.
In this case, the description is given above of the steps of the press diaphragm, however, there exists a manufacturing method for an oven diaphragm which is dried for one day or two days without pressing, that is, a so-called non-press diaphragm.
Further, the description is given above of the paper making diaphragm for the loudspeaker, however, a sub cone and a dust cap corresponding to the other paper making parts than the diaphragm are manufactured in accordance with a similar process.
In this case, as a prior art publication information, for example, there have been known a patent document 1 and a patent document 2.
In an acoustic business circle and an image business circle, there has been achieved a dramatic performance improvement on the basis of the significant development of the digital technology mentioned above. On the other hand, a tendency that a cost of a product becomes low is high, and in the loudspeaker used in the electronic device such as the acoustic device, the image device or the like, a market request for making the cost lower is significant.
In the conventional vibrating part for the loudspeaker which can satisfy the user needs, the paper making part formed by paper making the pulp material is a mainstream.
In the paper making part, since it is possible to vary a physical property value within a great range and in detail, the paper making part has an advantage that it is possible to fine adjust the characteristic as the loudspeaker and the sound quality, and has a problem that a lot of time is required for the beating step corresponding to a defect of the manufacturing method of the paper making part.    Patent Document 1: Unexamined Japanese Patent Publication No. 63-196790    Patent Document 2: Unexamined Japanese Patent Publication No. 2003-230197